The paper describes the Testbed for Advanced Transport Protocols and Architecture (TATPA) developed by the University of Bologna, inside the SatNEx (Satellite Network of Excellence) framework. The aim is to provide partners, and in general the scientific community, with a powerful and flexible emulation tool to evaluate new proposal at transport layer (both protocols and architectures). In accordance with our research interests, the testbed is focused on performance evaluation on heterogeneous networks that include satellite links. The testbed architecture is based on a cluster of Linux PCs and, in addition to some widely adopted networking tools (NistNet, Ipcrf), it also exploits software packages specifically developed by the authors (Multi TCP, PEPsal, released under GNU license). The testbed is controlled by remote through a web interface, which provides both users and administrators with a ubiquitous easy access to the testbed features. A dedicated PC, acting as testbed controller, hosts the web server and the control engine, developed in PHP and bash and based on a MySQL database. In the paper, a particular attention is devoted to the description of the innovative design and the many advanced features of this controller. An example of use, seen from the final user point of view, completes the description of the TATPA testbed.